Area Forecast Discussion
Issued by NWS State College, PA

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833 FXUS61 KCTP 270538 AFDCTP Area Forecast Discussion National Weather Service State College PA 138 AM EDT Sun May 27 2018 .SYNOPSIS... An upper level trough over the Ohio Valley will slowly push east across Pennsylvania on Sunday. Anomalous upper level ridging will build east across the region during the first half of next week, then moisture from the remnants of Alberto will stream into the region during the second half of the week, as the upper ridge shifts off the east coast. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Regional radar loop late this evening showing increasing coverage of showers across western Pa, as shortwave approaches from the Ohio Valley. Expect an increasing chance of showers across central Pa overnight, as this feature moves into the area. A blend of latest model guidance supports the highest (likely) POPs from the Laurels across the I-80 corridor. The one area of concern overnight will be the potential of locally heavy rainfall/flooding associated with any convection that may form late tonight over the southeast of the forecast area, where moderate capes and dewpoints near 70F are noted late this evening. Increasing cloud cover and dewpoints will result in a warm night, with minimum temperatures expected to range from around 60F over the northwest mountains, to near 70F across the southeast corner of the forecast area. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/... Sunday looks to be a cloudier and wetter day than Saturday, as slow moving upper trough combines with anomalous PWATs to produce a good chance of showers and thunderstorms across the entire region. Across the far eastern portion of the forecast area, the best chance of showers/storms may come during the morning hours with passage of shortwave. By afternoon, a back door cold front will push into this part of the state, diminishing the the threat of pm convection. Elsewhere, the best chance of showers/storms are expected during the afternoon, as diurnal heating results in moderate capes. PWATs on the order of +1 to 3 sigma will make any tstms potential heavier rain producers. Mainly cloudy skies and numerous showers will result in a cooler day than Saturday, with max temps mainly in the 70s. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... High pressure ridge over New England with low pressure off Long Island and a backdoor cold front through Central PA. Good chance for showers Sunday Night with the frontal zone. Frontal zone retreats east Monday leading to a drier day over all than Sunday but still a slight chance for some pop-up showers or thunderstorms. Drier into Tuesday with a strong ridge aloft ahead of the remnants of Alberto and a strong dry Canadian high pressure center dropping SE across New England and NY by Tuesday night into Wednesday. By Wednesday afternoon, this high moves far enough off the coast that deep southerly flow moves into Central PA with PWats increasing to over 2 standard deviations. Sub-tropical moisture and the remnant of Alberto will move in for the latter part of the week with unsettled warm and humid weather and a risk for heavy rain with any thunderstorms that occur. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... 06Z TAFS sent. Several bands of showers with isolated heavy downpours and perhaps a rumble of thunder at times. Main area of showers over southwestern PA having a hard time moving east of the mountains. Higher dewpoints across the southeast, with a drop off of dewpoints across the north. Thus would expect little organization to convection later today, thus used VCSH in most areas. CIGS still quite high, and fog is limited. For late afternoon, models hint that support for showers and storms fade across the west. Further east, left showers in until toward late evening. Main thing for Sunday night will be light winds with some fog, as any partial clearing will result in fog formation. Outlook... Mon-Tue...Mainly dry with VFR conditions during the day. Wide range of conditions at night with potential for fog formation. Wed...Generally VFR with local reductions in scattered showers/thunderstorms. Thu...Potential for more widespread showers and storms. && .CLIMATE... It has been a wet May across much of the region. As of Midnight, Williamsport rainfall for the month has been 7.05 inches. This is the 6th wettest May on record, and we still have a few days to add to the total. The wettest May was 1919 with 9.91 inches of rainfall. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Fitzgerald/RXR NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald LONG TERM...Watson/La Corte AVIATION...Martin CLIMATE...Martin is the U.S. government's official web portal to all federal, state and local government web resources and services.